wrap-iife.js

/**
 * @fileoverview Rule to flag when IIFE is not wrapped in parens
 * @author Ilya Volodin
 */

"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const astUtils = require("./utils/ast-utils");
const eslintUtils = require("eslint-utils");

//----------------------------------------------------------------------
// Helpers
//----------------------------------------------------------------------

/**
 * Check if the given node is callee of a `NewExpression` node
 * @param {ASTNode} node node to check
 * @returns {boolean} True if the node is callee of a `NewExpression` node
 * @private
 */
function isCalleeOfNewExpression(node) {
    const maybeCallee = node.parent.type === "ChainExpression"
        ? node.parent
        : node;

    return (
        maybeCallee.parent.type === "NewExpression" &&
        maybeCallee.parent.callee === maybeCallee
    );
}

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

module.exports = {
    meta: {
        type: "layout",

        docs: {
            description: "require parentheses around immediate `function` invocations",
            category: "Best Practices",
            recommended: false,
            url: "https://eslint.org/docs/rules/wrap-iife"
        },

        schema: [
            {
                enum: ["outside", "inside", "any"]
            },
            {
                type: "object",
                properties: {
                    functionPrototypeMethods: {
                        type: "boolean",
                        default: false
                    }
                },
                additionalProperties: false
            }
        ],

        fixable: "code",
        messages: {
            wrapInvocation: "Wrap an immediate function invocation in parentheses.",
            wrapExpression: "Wrap only the function expression in parens.",
            moveInvocation: "Move the invocation into the parens that contain the function."
        }
    },

    create(context) {

        const style = context.options[0] || "outside";
        const includeFunctionPrototypeMethods = context.options[1] && context.options[1].functionPrototypeMethods;

        const sourceCode = context.getSourceCode();

        /**
         * Check if the node is wrapped in any (). All parens count: grouping parens and parens for constructs such as if()
         * @param {ASTNode} node node to evaluate
         * @returns {boolean} True if it is wrapped in any parens
         * @private
         */
        function isWrappedInAnyParens(node) {
            return astUtils.isParenthesised(sourceCode, node);
        }

        /**
         * Check if the node is wrapped in grouping (). Parens for constructs such as if() don't count
         * @param {ASTNode} node node to evaluate
         * @returns {boolean} True if it is wrapped in grouping parens
         * @private
         */
        function isWrappedInGroupingParens(node) {
            return eslintUtils.isParenthesized(1, node, sourceCode);
        }

        /**
         * Get the function node from an IIFE
         * @param {ASTNode} node node to evaluate
         * @returns {ASTNode} node that is the function expression of the given IIFE, or null if none exist
         */
        function getFunctionNodeFromIIFE(node) {
            const callee = astUtils.skipChainExpression(node.callee);

            if (callee.type === "FunctionExpression") {
                return callee;
            }

            if (includeFunctionPrototypeMethods &&
                callee.type === "MemberExpression" &&
                callee.object.type === "FunctionExpression" &&
                (astUtils.getStaticPropertyName(callee) === "call" || astUtils.getStaticPropertyName(callee) === "apply")
            ) {
                return callee.object;
            }

            return null;
        }


        return {
            CallExpression(node) {
                const innerNode = getFunctionNodeFromIIFE(node);

                if (!innerNode) {
                    return;
                }

                const isCallExpressionWrapped = isWrappedInAnyParens(node),
                    isFunctionExpressionWrapped = isWrappedInAnyParens(innerNode);

                if (!isCallExpressionWrapped && !isFunctionExpressionWrapped) {
                    context.report({
                        node,
                        messageId: "wrapInvocation",
                        fix(fixer) {
                            const nodeToSurround = style === "inside" ? innerNode : node;

                            return fixer.replaceText(nodeToSurround, `(${sourceCode.getText(nodeToSurround)})`);
                        }
                    });
                } else if (style === "inside" && !isFunctionExpressionWrapped) {
                    context.report({
                        node,
                        messageId: "wrapExpression",
                        fix(fixer) {

                            // The outer call expression will always be wrapped at this point.

                            if (isWrappedInGroupingParens(node) && !isCalleeOfNewExpression(node)) {

                                /*
                                 * Parenthesize the function expression and remove unnecessary grouping parens around the call expression.
                                 * Replace the range between the end of the function expression and the end of the call expression.
                                 * for example, in `(function(foo) {}(bar))`, the range `(bar))` should get replaced with `)(bar)`.
                                 */

                                const parenAfter = sourceCode.getTokenAfter(node);

                                return fixer.replaceTextRange(
                                    [innerNode.range[1], parenAfter.range[1]],
                                    `)${sourceCode.getText().slice(innerNode.range[1], parenAfter.range[0])}`
                                );
                            }

                            /*
                             * Call expression is wrapped in mandatory parens such as if(), or in necessary grouping parens.
                             * These parens cannot be removed, so just parenthesize the function expression.
                             */

                            return fixer.replaceText(innerNode, `(${sourceCode.getText(innerNode)})`);
                        }
                    });
                } else if (style === "outside" && !isCallExpressionWrapped) {
                    context.report({
                        node,
                        messageId: "moveInvocation",
                        fix(fixer) {

                            /*
                             * The inner function expression will always be wrapped at this point.
                             * It's only necessary to replace the range between the end of the function expression
                             * and the call expression. For example, in `(function(foo) {})(bar)`, the range `)(bar)`
                             * should get replaced with `(bar))`.
                             */
                            const parenAfter = sourceCode.getTokenAfter(innerNode);

                            return fixer.replaceTextRange(
                                [parenAfter.range[0], node.range[1]],
                                `${sourceCode.getText().slice(parenAfter.range[1], node.range[1])})`
                            );
                        }
                    });
                }
            }
        };

    }
};